The only limitation is that the extension must be one of Rockbox's 'known' filetypes, as listed in filetypes.c. This does not include, for example, .config. It also recognises the firmware extensions (.ipod, .mi4 etc.).

Activation

In order to activate the filetype colours option, it has to be invoked from within a standard Rockbox configuration file (*.cfg). The easiest way is to create a new text file containg the following single line:

filetype colours: /.rockbox/themes/filename.colours

where filename is replaced by the filename you used when creating the .colours file. Save this file as colours.cfg in the /.rockbox/themes directory and then activate the config file from the menu as normal (Settings > Theme Settings > Browse Themes)